The present invention relates to a covering machine for packing boxes, in particular for covering boxes with a covering sheet on which glue has already been applied.
There are prior art so called “covering machines” for joining an erected box and a covering sheet to which glue was previously applied.
Examples of such machines were the subject matter of patents IT1224973 and IT1269105 by the same Applicant.
Such machines have a movement system with which the box is transported to a covering unit which applies the sheet on which glue has already been applied to the walls of the box to complete box covering.
The boxes are brought to the covering unit already joined to the respective covering sheet. In this situation, the box rests on the central portion of the inner surface of the covering sheet on which glue has already been applied, and with the respective opening facing upwards.
Covering machines have a mould, supported by respective movement elements which move the mould vertically. In this way, when the box joined to the respective covering sheet is brought to the covering unit, the mould is moved downwards and inserted in the box to push it into a forming cavity in which the covering sheet is applied to the walls of the box.
Covering machines also have rollers or brushes on the edges which form the forming cavity, designed to make contact with the outer surface of the covering sheet which is in contact with the corresponding walls of the box.
During the mould return stroke, the covered box is stopped by extractors which engage the box, allowing it to be removed from the mould. The covering machine then moves the box towards other processing stations.
However, prior art covering machines have the important disadvantage of not being suitable for covering “narrow” boxes, that is to say, boxes with small transversal dimensions.
Said disadvantage is mainly due to the dimensions of the mould movement and supporting elements, which must at least partly enter the forming cavity so that the box can be covered completely.
In this situation it should be noticed that the brushes or rollers which form the inlet edge of the forming cavity must be suitably spaced to allow said movement elements to pass between them.
Consequently, boxes with dimensions less than the minimum distance between the brushes, corresponding to the minimum dimensions of the movement elements, cannot be covered.